1. Field of the Invention
This invention relates to a method and apparatus of evaluating the mechanical properties of steel.
2. Description of the Prior Art
Of various properties of steel, mechanical properties such as strength and toughness are the most important. The tensile test is a test commonly conducted for the determination of steel strength. As is well-known, standard tension specimens are taken and prepared from a portion of the steel to be tested in accordance with such standards as ASTM and JIS. The specimens thus prepared are subjected to tensile and breaking loads using a tension testing machine under given conditions. Measures expressing the strength of steel to withstand deformation and fracture, such as tensile strength, yield point and elongation, are derived from the stress-strain curve and the shape and dimensions of the broken specimen established through the test.
The Charpy test is a test widely used to determine the toughness of steel. In the Charpy test, a specimen prepared to a standard is kept at a given temperature (commonly a low temperature below room temperature) and broken on a Charpy testing machine. The energy absorbed and the percent shear appearance of the fracture surface are determined.
In a steelmaking process, for instance, an inspection line is provided at the farthest end of its process line. A test specimen is taken from a portion of product, prepared as required, and put to mechanical tests to determine and guarantee the mechanical properties of the steel product being tested. Sampling and preparation of test specimens and implementation of mechanical tests require much time and money.